(1) Field of Invention
This invention relates to nonaqueous liquid fabric treating compositions. More particularly, this invention relates to phosphate free or low phosphate nonaqueous liquid laundry detergent compositions containing a suspension of a polyacetal carboxylate builder salt in nonionic surfactants which compositions are stable against phase separation and gelation and are easily pourable and to the use of these compositions for cleaning soiled fabrics.
(2) Discussion of Prior Art
Liquid nonaqueous heavy duty laundry detergent compositions are well known in the art. For instance, compositions of that type may comprise a liquid nonionic surfactant in which are dispersed particles of a builder, as shown for instance in the U.S. Pat. Nos. 4,316,812, 3,630,929 and 4,264,466 and British Pat. Nos. 1,205,711, 1,270,040 and 1,600,981.
The related pending applications assigned to the common assignee are Ser. No. 687,815, filed Dec. 31, 1984; Ser. No. 597,793, filed Apr. 6, 1984; now abandoned Ser. No. 597,948, filed Apr. 9, 1984; and now abandoned Ser. No. 725,455, filed Apr. 22, 1985.
These applications are directed to liquid nonaqueous nonionic laundry detergent compositions.
The washing power of synthetic nonionic surfactant detergents in laundry detergent compositions can be increased by the addition of builders. Sodium tripolyphosphate is one of the preferred builders. However, the use of sodium polyphosphate in dry powder detergents does involve several disadvantages such as, for example, the tendency of the polyphosphates to hydrolyse into pyro- and ortho-phosphates which represent less valuable builders.
In addition the polyphosphate content of laundry detergents has been blamed for the undesirably high phosphate content of surface water. An increased phosphate content in surface water has been found to contribute towards greater algea growth with the result that the biological equilibrium of the water can be adversely altered.
Recently enacted government legislation has been directed to reducing the amount of polyphosphates present in laundry detergents and in some jurisdictions in which polyphosphates have been a problem to require that the laundry detergents not contain any polyphosphate builders.
Liquid detergents are often considered to be more convenient to employ than dry powdered or particulate products and, therefore, have found substantial favor with consumers. They are readily measurable, speedily dissolved in the wash water, capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and are non-dusting, and they usually occupy less storage space. Additionally, the liquid detergents may have incorporated in their formulations materials which could not stand drying operations without deterioration, which materials are often desirably employed in the manufacture of particulate detergent products. Although they are possessed of many advantages over unitary or particulate solid products, liquid detergents often have certain inherent disadvantages too, which have to be overcome to produce acceptable commercial detergent products. Thus, some such products separate out on storage and others separate out on cooling and are not readily redispersed. In some cases the product viscosity changes and it becomes either too thick to pour or so thin as to appear watery. Some clear products become cloudy and others gel on standing.
In addition to the problem of settling or phase separation the nonaqueous liquid laundry detergents based on liquid nonionic surfactants suffer from the drawback that the nonionics tend to gel when added to cold water. This is a particularly important problem in the ordinary use of European household automatic washing machines where the user places the laundry detergent composition in a dispensing unit (e.g. a dispensing drawer) of the machine. During the operation of the machine the detergent in the dispenser is subjected to a stream of cold water to transfer it to the main body of wash solution. Especially during the winter months when the detergent composition and water fed to the dispenser are particularly cold, the detergent viscosity increases markedly and a gel forms. As a result some of the composition is not flushed completely off the dispenser during operation of the machine, and a deposit of the composition builds up with repeated wash cycles, eventually requiring the user to flush the dispenser with hot water.
The gelling phonomenon can also be a problem whenever it is desired to carry out washing using cold water as may be recommended for certain synthetic and delicate fabrics or fabrics which can shrink in warm or hot water.
The tendency of concentrated detergent compositions to gel during storage is aggrevated by storing the compositions in unheated storage areas, or by shipping the compositions during winter months in unheated transportation vehicles.
Partial solutions to the gelling problem have been proposed, for example, by diluting the liquid nonionic with certain viscosity controlling solvents and gel-inhibiting agents, such as lower alkanols, e.g. ethyl alcohol (see U.S. Pat. No. 3,953,380), alkali metal formates and adipates (see U.S. Pat. No. 4,368,147), hexylene glycol, polyethylene glycol, etc. and nonionic structure modification and optimization. As an example of nonionic surfactant modification one particularly successful result has been achieved by acidifying the hydroxyl moiety end group of the nonionic molecule. The advantages of introducing a carboxylic acid at the end of the nonionic include gel inhibition upon dilution; decreasing the nonionic pour point; and formation of an anionic surfactant when neutralized in the washing liquor. Nonionic structure optimization has centered on the chain length of the hydrophobic-lipophilic moiety and the number and make-up of alkylene oxide (e.g. ethylene oxide) units of the hydrophilic moiety. For example, it has been found that a C.sub.13 fatty alcohol ethoxylated with 8 moles of ethylene oxide presents only a limited tendency to gel formation.
Nevertheless, improvements are desired in both the stability and gel inhibition of low phosphate and phosphate free nonaqueous liquid fabric treating compositions.